Centrifugal advance device for an ignition distributor

ABSTRACT

A centrifugal advance device for an ignition distributor for an internal combustion engine wherein there are provided two main flywheel masses and two auxiliary flywheel masses. The main masses are each pivotable on a pin mounted on a plate which is connected to a drivable shaft and the auxiliary masses are coupled to the main masses. These masses are adapted on rotation of said shaft to displace a plate connected to a cam which is adapted to actuate a contact-breaker arm for obtaining a variation in the timing of the spark. The auxiliary masses are arranged to move the main masses in their angular displacement during a first stage of variation corresponding to a lower region of engine speed. After the engine speed has passed through this lower region, two abutments fixed to the plate connected to the control shaft prevent further angular movement of the auxiliary masses and main masses, thus providing an intermediate region of engine speed during which the timing of the spark does not vary. As the engine speed increases still further into an upper region spring means acting on said masses are overcome to permit further angular movement of the main masses and thus further angular movement of the plate connected to said cam.

Unite States Habert Feb. 6, I973 [75] Inventor: Roger I-Iabert,Epinay/Seine, France [73] Assignee: Ducellier & Cie, Paris, France [22]Filedz June 24, 1971 [21] Appl. No.: 156,207

[30] Foreign Application Priority Data July 10, 1970 France ..7025775[52] US. Cl. ..200/19 R, 200/31 CA, 64/25 [51] Int. Cl. ..II011h [58]Field of Search ..200/19 R, 30, 31, 80 R, 31 LA;

[56] References Cited UNITED STATES PATENTS 2,008,647 7/1935 Schneider..200/3l 3,202,777 8/1965 Scott ..200/3l 3,062,929 11/1962 Larges et a1...200/31 2,238,649 4/1941 Kishline ..64/24 2,219,480 10/1940 Hartzell eta1. .....64/25 2,533,755 12/1950 Bange ..64/25 3,139,081 6/1964 Tyzack..123/l48 R 3,430,459 3/1969 Hill ..64/25 3,482,559 12/1969 Salomon..l23/146.5 3,371,169 2/1968 Shiga et a1. ..200/19 R Primary Examiner-J.R. Scott Att0rneySughrue, Rothwell, Mion, Zinn & Macpeak [57] ABSTRACT Acentrifugal advance device for an ignition distributor for an internalcombustion engine wherein there are provided two main flywheel massesand two auxiliary flywheel masses. The main masses are each pivotable ona pin mounted on a plate which is connected to a drivable shaft and theauxiliary masses are coupled to the main masses. These masses areadapted on rotation of said shaft to displace a plate connected to a camwhich is adapted to actuate a contactbreaker arm for obtaining avariation in the timing of the spark. The auxiliary masses are arrangedto move the main masses in their angular displacement during a firststage of variation corresponding to a lower region of engine speed.After the engine speed has passed through this lower region, twoabutments fixed to the plate connected to the control shaft preventfurther angular movement of the auxiliary masses and main masses, thusproviding an intermediate region of engine speed during which the timingof the spark does not vary. As the engine speed increases still furtherinto an upper region spring means acting on said masses are overcome topermit further angular movement of the main masses and thus furtherangular movement of the plate connected to said cam.

3 Claims, 6 Drawing Figures Tr /mn PATENTEDFEB 6 I973 3,715,528

I SHEET 1 OF 2 INVENTOR PATENTED FEB. 6 I975 SHEET 2 OF 2 CENTRIFUGALADVANCE DEVICE FOR AN IGNITION DISTRIBUTOR The invention relates to acentrifugal advance device for an ignition distributor of an internalcombustion engine, the device being of the kind which comprises acentrifugal governor with weights which, when rotated by the controlshaft of the distributor, angularly moves a plate rigidly connected witha cam for actuating the contact-breaker arm in order to obtainvariations in the timing of ignition.

In certain internal combustion engines, the most favorable operatingconditions are only obtained if the variation of the timing of ignition(such variation depending on the number of'revolutions) does not takeplace in a linear manner, but is effected according to a stepped curve,i.e. in such a manner that there is, both in the lower region of thespeed range as well as in the upper region, a variation which doesdepend on the engine speed, but that there is not, any such variation inthe middle region of the speed range.

Variations of this type may be obtained, for example, by mechanismswhich cause the variation in the lower region of the speed range to beinitiated by one flywheel mass, namely a flywheel mass whose displace--ment is opposed by only a weak spring, and the variation in the upperregion of the speed range to be initiated by a second flywheel masswhose displacement is opposed by a more powerful spring, wherein in thecentral region of the speed range no variation can be produced becausethe centrifugal forces originating in this region are not capable ofmoving the second flywheel mass from its rest position.

Such an arrangement of this type causes an inbalance in the control ofthe distributor, an imbalance which acts in an unfavorable manner on thestability of the variation of the ignition when the engine is running.

Further, devices are also known for producing variations in the form ofa stepped curve with three stages of variation. It is also known, forexample, as described in French Pat. application No. 7,018,758, filedMay 22nd 1970, to add to the centrifugal governor, an intermediateplatewhich is pivotally mounted on the control shaft and accompanies theplate connected integral with the cam in its angular displacement duringthe first stage of variation under the joint action of a support memberand a spring subject to a certain initial tension. The intermediateplate presses against a fixed abutment on the plate connected integralwith the control shaft at a timing corresponding to the end of the firststage of variation, after which the tension of said spring and of aspring opposing the flywheel masses combine and oppose the centrifugalforces in order to obtain the second stage of variation until thecentrifugal forces,

increasing due to the increase in the number of revolutions, overcomethe tensions of said springs and determine the thirdstage of variation.

Although this makes it possible to solve the problem of inbalance of thedevice, the solution is not entirely satisfactory due'to the fact thatthe middle region of the speed range in which the moment of sparkingdoes not vary, is relatively limited.

The object of the present invention is to provide an improved form ofcentrifugal advance device which overcomes these problems.

According to the present invention, there is provided a centrifugaladvance device for an ignition distributor of an internal combustionengine of the kind comprising a centrifugal governor having rotatablemasses which are adapted to angularly displace a plate connected to acam which is adapted to actuate a contactbreaker arm for obtaining avariation in the moment of sparking dependent upon engine speed, suchvariation taking the form of a curve having three stages, namely a firstand 3* third stage, associated respectively with the lower and upperregions of the engine speed, during which the moment of sparking variesin dependence upon the number of revolutions, and a second stage,associated with an intermediate region of the engine speed and duringwhich the moment of sparking does not vary. The device comprises ashaft, a plate connected to said shaft, two main flywheel masses, eachpivotable on a pin mounted on said plate connected to said shaft, andeach arranged to act on the plate connected to the cam so as to toangularly to displace it, two auxiliary flywheel masses, coupled to themain flywheel masses, and spring means acting on said masses. Theauxiliary masses are arranged to drive said main masses in their angulardisplacement during the first stage of variation by exerting on themadditional centrifugal forces, there. Two abutments fixed to the plateconnected to the control shaft. are provided and against which theauxiliary flywheel masses bear respectively at a moment corresponding tothe end of said first stage of variation to prevent further. angularmovement of said auxiliary masses and further angular movement of saidmain masses until increasing centrifugal forces acting on the mainmasses due to an increase in the engine speed are sufficient to overcometension exerted by the spring means to permit further angular movementof said main masses and accordingly further angular movement of saidplate connected to said cam, corresponding to said third stage.

The invention will now be more particularly described with reference tothe accompanying drawings in which:

FIG. 1 is a view in longitudinal section of one example of a centrifugaladvance device in accordance with the invention,

FIG. 2 is a plan view of the present invention in th stationaryposition,

FIGS. 3, 4 and 5 are plan views of the device of FIG. 1 in threedifferent positions of the cam plate corresponding respectively to thethree stages of variation of the moment of sparking, and

FIG. 6 shows a curve of variation of the the timing of sparking in theform of a stepped curve which may be obtained by a device according tothe present invention.

The centrifugal advance device shown in the drawings has a shaft 1 whichis connected to a plate 2 supporting two pins 3 and 4 about which pivottwo main flywheel masses 5 and 6. A plate 7 connected to the cam 8, hastwo pins 9 and 10 which engage cam surfaces 1 l and 12 provided in themasses 5 and 6.

Two further or auxiliary flywheel masses 13 and 14 are coupled to themain flywheel masses 5 and 6 pivoting on the shafts 3 and 4. The furthermasses l3 and 14 are formed with apertures 15 and 16 through which passpins 17 and 18 connected to the masses Sand 6,

the ends of said apertures 15 and 16 limiting the amplitude of theangular displacement of the masses and 6 relative to the masses 13 and14. The amplitude of movement of said further masses l3 and 14 islimited by two abutments constituted by two brackets 23 and 24 producedby bending said plate 2. Two springs 19 and 20 have their endsrespectively hooked to the pins 17 and 18 connected to the masses 5 and6 and to brackets 21 and 22 formed by cutting and bending said plate 7connected integral with the cam 8.

If it is assumed that the shaft 1 of the distributor rotates in aclockwise direction, said further flywheel masses 1'3 and'14 are thusthe seat of centrifugal forces which tend to make them rotate about pins3 and 4 in the direction of the arrows f. However, the spring 20 actingon the pin 18 connected to the main flywheel mass 6, keeps the device inits initial position relative to the plate 2 so long as the speed ofrotation of the said shaft 1 does not reach a pre-determined value. Whenthe speed of rotation becomes greater than that chosen, said furtherflywheel masses 13 and 14 turn in the direction of the arrows f andduring this angular displacement drive the main flywheel masses 5 and 6through the intermediary of the pins 17 and 18 which engage the ends 15aand 16a of the apertures 15 and 16 (FIG. 2).

The main flywheel masses 5 and 6 are then driven by the further flywheelmasses 13 and 14 until said masses l3 and 14 contact the abutments 23and 24 integral with the plate 2 and, by means of the cam surfaces 11and 12 on which the pins 9 and 10 slide, force said cam plate 7 torotate about the control shaft 1 by a certain angle proportional to thespeed of rotation of the shaft, as determined by the profile of the camsll, 12 and the tension of the springs 19 and 20, thus modifying theangle of advance of the spark in proportion to the speed of the engine.

The amplitude of movement of the plate 7 connected to the cam 8,relative to the plate 2, corresponds to the first stage of variation ofthe moment of sparking as il- I lustrated by the curve A in FIG. 6.

As soon as the further flywheel masses 13 and 14 'come into contact withthe abutments 23 and 24 (FIG.

4), no further rotation of the plate 7 and cam 8 is produced for thetime between speeds N and N as shown in FIG. 6, even when the number ofrevolutions increases, since the centrifugal force developed by the mainflywheel masses 5 and 6 is insufficient to overcome the force exerted bythe springs 19 and 20. This will thus provide a second stage duringwhich the moment ofsparking does not vary as shown by line B of thecurve in FIG. 6.

It is only after a further considerable increase in the number ofrevolutions of the associated internal combustion engine (i.e. onincrease in speed of shaft 1) that masses 5 and 6 is limited by the ends15b and 16b of the apertures 15 and 16.

With a centrifugal advance device as abovedescribed, it is possible toobtain curves of variation of the timing of ignition in the form ofsteps without any inbalance in the control affecting the regulation ofthe timing of sparking and without any limitation of the amplitude ofthe stages of variations.

It is to be understood that the embodiment which has been describedabove referring to the accompanying drawings has been given only as anexample and is in no way limiting and that numerous modifications may beapplied without diverging from the scope of the present invention. Thus,in contrast to the embodiment described, the pins 17 and 18 connected tothe main flywheel masses and to which the springs 19 and 20 are hooked,may be connected to the further or auxiliary flywheel masses, with pinsextending through apertures provided in the main flywheel masses.

I claim:

1. A centrifugal advance device for an ignition distributor of aninternal combustion engine of the type including a centrifugal governorhaving rotatable masses which are adapted to angularly displace a plateconnected to a cam, said cam being adapted to actuate a contact-breakerarm for obtaining a variation in the timing of the moment of sparkingdependent upon engine speed, comprising a rotatable shaft, a plateconnected to said shaft, two main flywheel masses, each main mass beingpivotable on a pin mounted on said plate connected to said shaft andbeing operatively connected to said plate so as to angularly displacesaid plate when said main masses are pivoted on said pins, two auxiliaryflywheel masses operatively coupled to said two main flywheel masses,spring means operatively connected between said masses and said plate,and further including two abutments fixed to said plate adjacent thepaths of movement of said auxiliary masses, said auxiliary massesabutting said abutments upon moving a first predetermined angulardistance jointly with said main masses, said abutments preventingfurther angular movement of said auxiliary masses, further angularmovement of said main masses being prevented by the force of said springmeans for a predetermined period of engine speed increase untilincreasing centrifugal forces acting on said main masses due toincreases in the engine speed are sufficient to overcome tension exertedby said spring means to permit further angular movement of said mainmasses and thus further angular movement of said plate connected to saidcam.

2. A centrifugal advance device according to claim 1, wherein eachauxiliary mass is pivoted on the same pin as a main mass to which it iscoupled, each auxiliary mass and the associated main mass being coupledtogether by a further pin which connected to one of said masses andextending through an aperture formed in the other mass coupledtherewith, one end of a spring forming part of said spring means beinghooked to one end of said further pin.

3. A centrifugal advance device according to claim 1 wherein said mainand auxiliary masses in conjunction with said spring means and saidabutments act to vary the timing of the moment of sparking in threestages, the first and third stages being associated respectively withthe lower and upper regions of the engine speed, the moment of sparkingin said first and third stages being dependent upon the number ofrevolutions of said engine, the second stage of said curve beingassociated with an intermediate region of the engine speed, the timingof the moment of sparking remaining constant in the intermediate regionof said curve.

1. A centrifugal advance device for an ignition distributor of aninternal combustion engine of the type including a centrifugal governorhaving rotatable masses which are adapted to angularly displace a plateconnected to a cam, said cam being adapted to actuate a contact-breakerarm for obtaining a variation in the timing of the moment of sparkingdependent upon engine speed, comprising a rotatable shaft, a plateconnected to said shaft, two main flywheel masses, each main mass beingpivotable on a pin mounted on said plate connected to said shaft andbeing operatively connected to said plate so as to angularly displacesaid plate when said main masses are pivoted on said pins, two auxiliaryflywheel masses operatively coupled to said two main flywheel masses,spring means operatively connected between said masses and said plate,and further including two abutments fixed to said plate adjacent thepaths of movement of said auxiliary masses, said auxiliary massesabutting said abutments upon moving a first predetermined angulardistance jointly with said main masses, said abutments preventingfurther angular movement of said auxiliary masses, further angularmovement of said main masses being prevented by the force of said springmeans for a predetermined period of engine speed increase untilincreasing centrifugal forces acting on said main masses due toincreases in the engine speed are sufficient to overcome tension exertedby said spring means to permit further angular movement of said mainmasses and thus further angular movement of said plate connected to saidcam.
 1. A centrifugal advance device for an ignition distributor of aninternal combustion engine of the type including a centrifugal governorhaving rotatable masses which are adapted to angularly displace a plateconnected to a cam, said cam being adapted to actuate a contact-breakerarm for obtaining a variation in the timing of the moment of sparkingdependent upon engine speed, comprising a rotatable shaft, a plateconnected to said shaft, two main flywheel masses, each main mass beingpivotable on a pin mounted on said plate connected to said shaft andbeing operatively connected to said plate so as to angularly displacesaid plate when said main masses are pivoted on said pins, two auxiliaryflywheel masses operatively coupled to said two main flywheel masses,spring means operatively connected between said masses and said plate,and further including two abutments fixed to said plate adjacent thepaths of movement of said auxiliary masses, said auxiliary massesabutting said abutments upon moving a first predetermined angulardistance jointly with said main masses, said abutments preventingfurther angular movement of said auxiliary masses, further angularmovement of said main masses being prevented by the force of said springmeans for a predetermined period of engine speed increase untilincreasing centrifugal forces acting on said main masses due toincreases in the engine speed are sufficient to overcome tension exertedby said spring means to permit further angular movement of said mainmasses and thus further angular movement of said plate connected to saidcam.
 2. A centrifugal advance device according to claim 1, wherein eachauxiliary mass is pivoted on the same pin as a main mass to which it iscoupled, each auxiliary mass and the associated main mass being coupledtogether by a further pin which connected to one of said masses andextending through an aperture formed in the other mass coupledtherewith, one end of a spring forming part of said spring means beinghooked to one end of said further pin.